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Noise Pollution Impacts Nature

Manmade Noise Pollution is Changing the Song of the Grasshopper

There’s more bad news for the earth’s urban fauna, subjected to man-made noise pollution levels that already have birds changing the tune of their chirp to be heard above the din of traffic, machinery, industry, music and everything else we subject them to.

It appears that male grasshoppers are responding to road traffic noise in their environment by changing the pitch of their songs just so their voices can be heard by the lady grasshoppers. In fact, a new study published in the journal Functional Ecology is the first to confirm what scientists have long suspected – the male bow-winged grasshopper has altered the actual pitch of his ballads by raising the pitch of its lower notes in order to rise to a mini-crescendo, according to study scientists from the University of Bielefeld in Germany.

That’s right, the bow-winged grasshopper was blessed by nature to create songs that include low and high frequency elements, and we have all heard that distinctive choral routine at some point in our lives. I remember the first time I was made aware of it; our family spent summers in a place called Eagle River Wisconsin – serious “Northwoods” wilderness so far north, its winters are subarctic. One summer evening at dusk, I think I was about six, my dad got me to listen to an unfamiliar sound I might not have noticed had he not shared the moment with me.

I remember how the sweeping notes that distinctly changed pitches made my jaw drop – it was a cloud of grasshoppers. It was the first time it occurred to me that bugs could make any sounds at all, much less relatively sophisticated harmonized sounds.

Grasshoppers sing!

Ulrike Lampe, a research scientist at the University of Bielefeld in Germany, led the new study on grasshoppers responding to noisy environments, said that the creatures have adapted to noise pollution encroaching on their habitats by increasing the volume of the lower-frequency part of their songs. Dr. Lampe explains that this made sense to her group of research scientists because it was already known to them that traffic noise can veil sounds in that spectrum of frequency.

Studies on the effects of man-made noise pollution on wildlife and domestic animals have increased in recent decades, but this appears to be the first study to focus on the effects of noise on invertebrates such as insects.

“We know that birds shift the frequencies of their songs or use songs with higher mean frequencies under noisy conditions,” Dr. Lampe says. “Some frog species alter their calling rate in response to high background noise levels, and whales have also been found to change the pitch of their acoustic communications as high-volume noise from military submarines, ships, and underwater explosions.

This bow-winged grasshopper that the University of Bielefeld scientists studied is a common species; It grows to about 1.5cm in length, and comes in a variety of colors from green and brown to red and purple. They make their songs by rubbing a toothed file on their hind legs against the “bow” of a bulging vein in their front wings in a similar fashion to playing a cello. And it’s the males doing all the singing during the months of July and September in hopes of attracting the ladies. Ordinarily, the male grasshopper sings two-second-long “phrases” in each of the songs in his repertoire, which rise in volume as it nears the end. A slow “ticking” sound starts out each phrase, increasing in speed and volume and rising to a crescendo of buzzing near the end.

This is a remarkable feat of nature, as we all know, but it is almost bad news to anyone who is learning about the toll noise pollution is taking on the voice of the grasshopper, along with the scrub jay, the pinyon tree, the nightingale, and the remaining host of flora and fauna adversely affected by our noise. Dr. Lampe and her colleagues thought that the low-frequency of the grasshopper’s bass signals might be masked by traffic noise which is why they chose this species for the study.

Bow-winged grasshoppers make a good test subject for the effects of noise pollution on an insect as their process for sexual selection depends upon being able to hear each other. Female grasshoppers are able to respond to a male’s mating song with their own low frequency acoustic signal, according to Dr. Lampe.

“We thought about the possibility that this lower part of the frequency spectrum might be degraded or masked by (manmade noise), such as traffic noise,” she said.

The study’s scientists collected 188 male bow-winged grasshoppers, half from habitat close to a busy roadway, and the other half from open grassland with no manmade noise pollution entering their space. Then they compared the range and frequency of their songs – almost 1,000 songs were recorded in all!

Dr. Lampe said they found that the grasshoppers exposed to traffic noise were proven to have changed the pitch of their songs, which could have a serious effect on their ability to find mates.

“Increased noise levels could affect grasshopper courtship in several ways,” Dr. Lampe writes.   “It could prevent females from hearing male courtship songs properly, prevent females from recognizing males of their own species, or impair females’ ability to estimate how attractive a male is from his song.

“We don’t know this, yet. We want to find out more about female preferences for spectral parameters of the songs and whether traffic noise affects these preferences in some way,” she added.

All I can think of is that day I realized that what I was hearing was the remarkable orchestra-like precision of that cloud of grasshoppers in Eagle River, Wisconsin, and how scary it seems that future generations of children may never have the opportunity because man made noise pollution changed the way grasshoppers court.

Noise Pollution is a Growing Threat to Fish and Other Marine Life

When I was a kid, my dad kept a tropical fish tank that he doted over. I recall tapping on the glass of the tank one time to catch the attention of an aloof angel fish, but my dad stopped me before I could elicit a response from the beautiful creature – exquisite, really, all bolts of vibrant color and gently cascading Ventral fins (angel whiskers). Anyway, my dad told me that tapping on the glass could actually harm the fish physiologically, and he followed with an explanation of sound waves through water.

I have been conscientious of the vulnerability of fish in tanks ever since. I can’t stand being in a pet shop and witnessing people tap on the fish tanks. But the fish don’t exhibit discomfort, so I doubt that a lot of people realize the harm they do when they tapping.

I only mention this because of a new study I found on the growing threat of man-made noise pollution to wildlife – most specifically marine life. Traffic noise, industrial noise, the everyday noise pollution that is part and parcel to urban life – these sounds are impacting marine mammals, many of which depend on echolocation (echo-location) to decipher sounds and echoes that help them determine the direction and distance of things like dinner, predators, and mates.

But a University of Maryland Biology professor spent decades researching bioacoustics and the effects of man-made noise pollution on fish, and the underwater world that he had assumed was silent when he was a child turned out to be a very noisy place indeed.

Arthur Popper, the University of Maryland professor, spoke to a group at the International Congress of Neuroethology in Maryland last August about how man-made noise is affecting fish in their native underwater habitats. According to Popper, manmade noise pollution is interfering with behavioral patterns of fish in much the same way it’s affecting birds and other wildlife on land. Most fish actually hear well, and since light doesn’t travel very deep in water fish have little to no visual perspective to rely on. That means they rely on sound to detect predators, find food, communicate, and navigate their environment.

Popper studied under the man who founded the field of marine bioacoustics, William Tavolga, and along with other marine biologists they were able to demonstrate just how important sound is to fish. Believe it or not, fish produce sound – more than 800 species of fish are known to produce sounds! Those fish that do have voices speak up for different reasons – when they are fighting a predator, of battling over food or territory for instance.

Differences if hearing sensitivity varies from one fish species to another.

Popper And other scientists in the Netherlands, Germany and Belgium completed a study on the impact of man-made noise on fish, and the results tell us that noise pollution from oil and gas rigs, ships, construction and sonar are interfering with spawning, the fish’s ability to avoid predators, and even school. Fish have proven to school less in areas where mad-made noise levels are high. They avoid or abandon historic spawning sites and change migration routes because of noise. Environmental noise pollution was even found to cause stress responses in the fish’s endocrine systems and other systems that can effect health. Fish exposed to extremely loud noise can experience hearing loss, bleeding, tissue damage and death.

In his research, Popper also investigated the effects of seismic air guns used in oil exploration, and high intensity sonar and pile driving, used in bridge, pier, and wind farm construction on fish health and behavior. Popper concluded that behavioral and physiological damage to fish caused by man-made noise pollution may vary according to intensity of the noise, length of exposure and a rage of other factors that scientists are just beginning to look into.

Popper and his colleagues say that more basic research needs to be done to determine the lasting effects of noise pollution on fish, and to better understand what and why fish hear in order to evaluate and mitigate noise pollution in various marine environments. The earth grows noisier each year, and studies have proven that certain bird species have stopped mating due to noise pollution. In fact, noise pollution has been proven to wreak havoc on a variety of animal and plan ecosystems. Now it seems that fish could be facing the same species-threatening consequences of man-made noise pollution.

Manmade Noise Pollution Has Birds Singing a Different Tune

Last week, I wrote about the noted affects of noise on the iconic pinyon tree of the American Southwest Mesas. In all, the deterioration of the pinyon is already adversely affecting  about 1,000 species of fungi, insects, arthropods, mammals and birds depend on tree for their survival.

This week, new findings are beginning to prove that noise pollution is interfering with the reproductive choices of birds as well.  Male birds are the crooners in nature; the tone of their song plays a critical role in the mating protocol of most feathered species. Birds in urban communities and communities exposed to high decibel traffic and industrial noise are singing and chirping in a different tune than that which nature provided, in order to be heard above the din of the manmade noise with which they must now compete. In the process of changing their singing tone to be able to hear one another, they are losing their natural key – their specific mating call that serves to attract females. If they were to quit fighting the noise and maintain their natural singing voices, chances are they won’t be heard by potential mates at all.

According to Wouter Halfwerk, a behavioral ecologist at Leiden University in the Netherlands, lower frequency singing among male song birds has the vibe that brings the lady birds calling. Let’s call it the Barry White songbird vibe.  When given the choice between a low pitched Barry White vibrato and, say, a high pitched Barry Gibb staccato, the lady birds choose Barry White every time.

“If females can hear all song types equally well, they will go for the sexy ones,” Halfwerk says. “But if they cannot hear the sexy ones well anymore, then they might just go for the songs they can still hear.

“It could very well be that noise pollution is interfering with reproductive decisions by females.”

However, females are working a little harder than  they used to, to identify quality mates who are practicing their sexy voices and keeping them in tune. Halfwerk, along with a group of scientists studying the effects of  manmade noise on animals, did some spying and discovered that certain females may be canoodling with another male on the sly if their own mate’s singing tone isn’t doing it for them.

Apparently these untrustworthy female birds are sneaking out of the nest in the early morning hours, chasing after a nearby Barry White crooner – a rendezvous which for birds only takes about 60 seconds – and she’s back in the nest, never missed. That’s right – researchers surmised that the males that sang in higher (Barry Gibb) registers were more likely to be cuckolded than the low-throated crooners.

Since they wouldn’t be real researchers if they didn’t consider every opportunity to challenge their hypothesis, the scientists conducted paternity tests on the offspring and discovered that about 30% of the nest-dwelling partner males were not the baby daddy. Overall, the males that sang in new, high pitched frequencies to be heard above the manmade noise – most notably around the time that the lady birds were at their most fertile – were the males that ended up unwittingly helping to raise another bird’s offspring.

Next, these same researchers fitted nests with microphones and speakers, and tracked the females while they were subjected to different recordings of their mates’ calls. The researchers also funneled in noise that mimicked traffic sounds to see if it had any effect on the females.

With urban noise in the mix, the females responded to their mates’ high-pitched calls more often than the lower, sexier (Barry White) calls — probably because they could hear them better.

The results of these studies have confirmed that while noise pollution does interfere with the birds’ ability to communicate during their high-stakes mating games, they’re still managing to mate. Still, previous studies have shown that a variety of birds can suffer when they change their songs, according to Erin Bayne, an ornithologist at the University of Alberta. The new study is one of the first to explain why.

As more research data is completed on the effects of manmade noise on animals, nothing is being done to temper noise pollution, which is as insidious to human health as it is to a bird on the wire.

When a Tree Falls in the Forest: How Man Made Noise Impacts Wildlife

If a tree falls in the forest, and no one is around to hear it, does it make a sound?

You don’t need humans to confirm the sound of a falling tree, or any noise for that matter, as scientists will tell you. The proof is in the behavior modifications that noise has caused in the forest’s wildlife.

The impact of noise on wildlife – from birds, to elk, to whales – has garnered plenty of attention from scientists in recent years. What may or may not be surprising is that studies are showing  that animals with habitats in natural settings are modifying their behaviour in response to human noise.

You know that “fight or flight” instinct that we all experience when a door unexpectedly slams, cars collide, jackhammers tear up the street or an ambulance races by, sirens blazing? The “fight or flight” instinct in wildlife is being wildly over-stimulated, and although sometimes their behavior modification is brief, it nonetheless happens. This is a real problem, as planet earth seems to be buckling to the impact of man-made noise on its ecosystems.

A 2009 article in Park Science describes animals reacting to human commotion in the reflexive manner of a creature suddenly threatened by predators. In humans, we know that these responses, when over stimulated for ongoing stretches of time, can lead to elevated blood pressure, stress, sleeplessness, depression and even heart disease. In wildlife, the constant flare-ups of anti-predator behavior interferes with their ability to perform normal functions, like foraging for food and taking care of their young.

The fear among scientists is that, as human-caused noise disturbances to wildlife become more frequent, populations of species could start to fade.

In Northern California – north of San Francisco, Muir Woods presents as a redwood-vaulted oasis, a place so silent that the air can be heard circulating around the redwood branches, and the gurgling of Redwood Creek is unmistakable and exhilarating. One of the first things visitors to Muir Woods National Monument in Marin County notice is a noise level monitor.

This place wasn’t always this quiet.

Back in 2001, Muir Woods had already been abandoned by the native otter population decades earlier, and pileated woodpeckers had abandoned the national park as well. A familiar pair of northern spotted owl – endangered species, in fact – were not frequenting the redwood cove as often as they once had, and park rangers were growing concerned.

Adding insult to injury, an asphalt walkway that had been installed was interfering with the growth of the redwood’s surprisingly shallow root systems, causing at least one of the redwoods – age somewhere between 500 and 1,200 years old – to fall.

Still, the man-made noise issue was the most worrisome, as the clamor of garbage can lids and park maintenance vans infested the park. Tying its proverbial noose, it seemed, was the park’s proximity to a metropolitan area of seven million people.

For decades, park rangers and scientists have been worried about the affects of human noise on wildlife, but little was done about it. Eventually, however, an effort to restore the Muir Wood’s natural sounds took hold.

Slowly, mechanical sounds were silenced, and park visitors followed suit. With a concerted effort, human noise was all but squelched. Signs posted near Cathedral Grove in the center of the park request silence from visitors. The decibel meter near the gift shop entrance that measures the voices of visitors had one park visitor commenting that they could see themselves crunching on potato chips, as the decibel meter jumped with every crunch.

Today, there are times when the quiet in the park is so absolute, it seems possible to hear a banana slug slither by. According to scientists, this level of quiet is critical to the well-being of the native wildlife, which is recovering from the man-made cacophony that threatened its existence not too long ago.

Officials at some of the country’s national parks have worried about noise, and some have taken steps to make changes. Noise issues vary dramatically from one park to another. In the Florida Everglades, generators have been silenced at a campground, and park caretakers are trying to negotiate with airboat operators to measure the impact of their fans – which can mimic the sound of jet engines – to see if the noise they generate can be reduced. They have also approached officials at Homestead Air Force Base south of Miami about the timing of the sonic booms that shake the saw grass.

Noise reduction measures are being taken at some national parks, while there are high profile noise battles going on at others.

Park managers at the Grand Canyon want to require aircraft operators to shift to quieter planes, fly higher above the canyon’s northern rim, and refrain from flying at dawn or dusk. Senator John McCain, R-Arizona, has introduced legislation that would not only preempt the park’s plan to reel in aircraft noise, but would consider noise standards met if for at least 75 percent of the day, 50 percent of the park is free of commercial air tour noise.

Arizona environmental organizations have denounced McCain’s proposal, calling it a give-away to the air tour operators and an excuse to redefine what constitutes natural quiet.

A McCain spokesperson says the amendment was a measure to protect tourism jobs.

One of the most remarkable outcomes of the Muir Woods study comes from a year-long inventory taken of all sounds, natural and otherwise, in four places in the park. It was discovered that noise from the parking lot and gift shop bled a quarter-mile into the forest.

The parking lot was moved about 100 yards farther from the entrance, an ice machine was removed and the decibel meter was installed.

Park rangers are still establishing the affect that the reclaimed quiet has had on the park’s wildlife, since other clean up procedures were enacted at the same time, including removal of invasive weeds, elimination of the asphalt walkway, and installation of a new boardwalk that prevents visitors from walking on the forest’s spongy, porous moss-covered floor.

They say they don’t know the results yet. But otters have returned after a 74-year absence, and chipmunks are coming back as well.

In fact, two breeding pair of the rare, spotted nocturnal owls are inhabiting the Muir Woods site today.

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2017-10-26T14:49:05+00:00